Introduction
Choosing the right underground piping for a fuel station is one of the most important decisions an owner, engineer, or installer will make. The piping system carries gasoline, diesel, and other fuels from the tank to the dispenser, and it sits buried in the ground for decades. Once the trench is closed, repairs become expensive and disruptive. This article explains how the Ai Yuan range of composite underground pipes from Luoyang Wohong Petrochemical is designed, how to select the right specification, and what to check during installation and maintenance.
What the Ai Yuan Composite Pipe Is Made Of
The Ai Yuan underground pipe is a composite structure produced on an extrusion line. It combines several materials into one wall:
- HDPE (high-density polyethylene): the base structural layer, giving the pipe strength, flexibility, and long-term chemical resistance.
- EVOH (ethylene vinyl alcohol): a barrier layer that sharply reduces fuel permeation through the pipe wall, helping control vapor loss in underground service.
- Conductive masterbatch: dispersed in the material to help dissipate static charge that can build up as fuel moves through the pipe.
- Imported adhesive: bonds the layers together so the composite does not delaminate under pressure, temperature changes, or ground movement.
All fittings in the Ai Yuan system are made from imported PE resin, and all are electrofusion fittings, which means they are joined using heat rather than glue or mechanical seals.
Understanding the Product Range
Ai Yuan pipes are supplied in two basic forms: double-wall composite and single-wall. The choice depends on the application and whether you need secondary containment around the fuel line.
The available specifications are summarized below:
| Model | Type | Form |
|---|---|---|
| 125/110 | Double-wall composite | Straight pipe, 6 m per length |
| 110 | Single-wall composite | Straight pipe, 6 m per length |
| 90 | Single-wall composite | Straight pipe, 6 m per length |
| 75/63 | Double-wall composite | Coil (100 m, 75 m, or 50 m per coil) |
| 75/63 | Double-wall composite | Straight pipe, 6 m per length |
| 63 | Single-wall composite | Coil and straight pipe available |
| 65/54 | Double-wall composite | Coil (100 m or 50 m per coil) |
Note these key points when reading the table:
- Double-wall (secondary containment) lines such as 125/110, 75/63, and 65/54 have an inner fuel carrier and an outer containment pipe. They are typically used between the tank and the dispenser sump.
- Single-wall lines such as 110, 90, and 63 are often used in vent lines, fill lines, or sections where secondary containment is not required by the project design.
- Coil supply lets you run long continuous runs for some sizes, reducing the number of joints underground. Straight pipe is preferred when the trench layout has many fittings and changes in direction.
Electric Fusion vs. Glue and Mechanical Fittings
Every Ai Yuan fitting is an electrofusion fitting. In electrofusion, the fitting contains an embedded heating element. A fusion unit passes current through the element, melting the inner surface of the fitting and the outer surface of the pipe so the two fuse into one continuous piece of plastic.
Why this matters for underground fuel service:
- No solvents or adhesives that could fail or leach over time.
- Strong, repeatable joints when the correct fusion time and temperature are used.
- Traceability: each fusion is documented with time and temperature, which supports quality control on site.
Electrofusion is the method recommended for fuel piping because the joint becomes part of the pipe wall rather than a separate weak point. Mechanical couplings and glued joints rely on surface contact and can loosen as the ground expands and contracts.
Selecting the Correct Specification
Choosing the right model and form comes down to a few practical questions:
1. Where is the pipe being used?
Between the tank and the dispenser, designers usually specify a double-wall product with secondary containment to catch any leak in the inner pipe. To the tank, on the vent or fill side, a single-wall product may be sufficient depending on the overall station design.
2. What is the distance to cover?
For long runs with few fittings, coil supply minimizes joints and speeds up installation. For shorter runs with many direction changes, straight pipe in 6 m lengths gives you more flexibility to cut and fit precisely.
3. What are the site conditions?
Coiled pipe simplifies transport and installation on tight sites, but it is slightly harder to straighten and lay in a clean line. Straight pipe holds its shape better and is easier to grade accurately on a sloped trench.
Installation Best Practice
The performance of any underground pipe depends on how it is installed. Follow these points for a reliable Ai Yuan system:
Trench preparation
Excavate the trench to the finished depth, remove sharp stones and debris, and provide a clean, level bed. Bedding material should be free of large rocks that could concentrate pressure on the pipe wall.
Handling and placement
Use appropriate lifting methods and do not drag pipe over sharp edges. Keep the pipe clear of welding sparks, open flame, and heavy equipment during placement. Inspect each length and fitting before installation for cuts, gouges, or foreign material.
Electrofusion joining
Clean the pipe end and the inside of the fitting, mark the insertion depth, and clamp the fitting in place. Use a fusion unit matched to the fitting specification and record the fusion time and temperature for each joint. Allow the joint to cool completely before handling the assembly.
Backfill
Backfill in layers, compacting gently around the pipe. Avoid dropping large or sharp material directly onto the pipe. The first layers should use screened, fine-grained fill to protect the pipe before heavier cover is added.
Maintenance and Inspection Guidelines
Underground piping is rarely inspected after burial unless a problem is suspected, but routine checks help extend service life:
- Leak detection: If the system uses double-wall pipe with a monitoring point, test the interstice according to the project schedule.
- Dispenser and tank sumps: Keep sumps clean and check for liquid, which may indicate a leak in a connected line or fitting.
- Ground movement: After significant excavation, settlement, or nearby construction, check exposed sections and access points for visible stress or damage.
- Fusion records: If a joint is later suspected of leaking, the recorded fusion parameters help determine whether the joint was completed correctly at installation.
Cost Considerations Over the Life of the Station
Upfront material price is only part of the story. Underground fuel piping is expensive to rework because the cost includes excavation, disruption to station operations, and downtime. A composite pipe that fuses into a continuous, low-permeation system can save money by reducing the number of weak joints and by better controlling vapor loss over the years of service.
When comparing quotes, evaluate the delivered specification, the form of supply (coil vs. straight), the joining method, and the availability of matching electrofusion fittings from the same manufacturer. A complete, consistent system is generally easier to install and maintain than a mix of components.
Conclusion
The Ai Yuan range from Luoyang Wohong Petrochemical gives station owners and contractors a clear set of choices for underground fuel piping. By understanding the multi-layer construction, matching the model and form to the application, and following sound installation and maintenance practice, you can build a piping system that performs reliably under buried service conditions.